20863821 has 32 divisors (see below), whose sum is σ = 31518720. Its totient is φ = 12168000.

The previous prime is 20863813. The next prime is 20863831. The reversal of 20863821 is 12836802.

It is not a de Polignac number, because 20863821 - 2³ = 20863813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20863831) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 138096 + ... + 138246.

It is an arithmetic number, because the mean of its divisors is an integer number (984960).

Almost surely, 2^20863821 is an apocalyptic number.

It is an amenable number.

20863821 is a deficient number, since it is larger than the sum of its proper divisors (10654899).

20863821 is a wasteful number, since it uses less digits than its factorization.

20863821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297.

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 20863821 is about 4567.6931814648. The cubic root of 20863821 is about 275.2947627293.

The spelling of 20863821 in words is "twenty million, eight hundred sixty-three thousand, eight hundred twenty-one".